Smule, a San Francisco maker of musical apps, has generated a virtual symphony over the past few years, turning mobile phones into pianos, drums, guitars, ocarinas and even T-Pain rap-style vocals.

Now Smule is joining one of the more crowded frays in the app world, taking its musical chops into the chase for the latest high-tech holy grail - something pundits have dubbed "Instagram for video." Ever since the slick sepia-filtering, photo-sharing app Instagram was bought by Facebook for $1 billion dollars last year (later adjusted to $700 million, thanks to the struggles of Facebook stock), plenty of companies have taken a stab at creating another viral hit, this time using video.

Contenders include Socialcam, acquired by Autodesk for $60 million last year; Tout, which serves up 15-second videos and has been adopted by some major media sites; and Twitter, which, naturally, made Tout's short videos seem like Cecil B. DeMille epics with Vine, a six-second video app.

One of the most promising is "CineBeat," developed by Parag Chordia, who holds a doctorate from Stanford and is chief scientist at Smule. (Smule initially named the app Strum, but that proved not only a poor fit, but a trademark problem.) "CineBeat" was released in December, and already has 1.9 million users. It lets you put Instagram-style filters on your videos, provides a musical soundtrack, and gives users a variety of iMovie-style editing tools that can be implemented with a click of a button on a mobile phone.

Audio and video

"We didn't start out thinking about Instagram," Chordia said. "We started with music, and thought, 'This would be more compelling if we had a visual component.' Then we thought the converse: Video would be more compelling if it had an audio component."

Chordia had already developed Songify and LaDiDa, apps that take spoken words and convert them into music. By incorporating video, he's made it possible for any clip to become a music video.

Chordia's key partner is Ge Wang, who co-founded Smule when he developed the Ocarina app. That was after he'd already pioneered the convergence of computers and music with ventures like the Stanford Laptop Orchestra and MoPhO, the Mobile Phone Orchestra. In 2011, Smule acquired Chordia's company Khush, where Songify was developed.

"There are really only a handful of people on this planet who have the computer signal-processing chops, the creativity and the ability to build products," said Jeff Smith, Smule's CEO. Both Chordia and Wang have each developed products that have been installed on nearly 50 million cell phones. "Those are big numbers in our space," Smith said.

Venture investment

Smule has raised more than $25 million in venture capital since its founding in 2008, according to VentureBeat. That investment comes with some risks, according to Brian Zisk, executive director of the SF Music Tech Summit. "VCs want a half-billion-dollar exit, and it's going to be very difficult for them as an app company to build that sort of value," Zisk said.

Smith disagreed. "Music is a $100 billion a year market and growing," he said. "If we succeed in redefining this market, we will make our investors money. It appears we are on our way."

The company's gross sales topped $12.6 million last year, and Smith estimates they'll reach $20 million this year. It has 66 employees, all but 10 in San Francisco. On Sunday, Smule hit 100 million downloads, and it has 12 million monthly active users. "It took us three years to get to our first 10 million downloads, and less than two years to grow to 100 million downloads," Smith said.

While Zisk praised Smule for its technology, he said it's mostly used to build "toys," as opposed to apps professional musicians would use. Jeannie Yang, Smule's chief design officer, said the business model has evolved from charging for apps to a new "freemium" model, in which the app is free, but extras within the app cost money.

Chordia and Wang did not overlap at Stanford, but instead ran into each other at conferences, and first collaborated on a National Science Foundation grant in 2010. Chordia sees Wang as a sounding board and a fellow experimenter.

"There are not that many people who are truly creative," Chordia said. "We're trying to invent something new. We're not taking a known model and tweaking it, like a lot of app makers do with social games. We're starting stuff from scratch."

Academics at heart

Both men are, at heart, academics, but were lured into the business world. "Sometimes I feel I don't really know exactly what it is that I do," Wang said. "If we knew what we were doing, it wouldn't be research."

Chordia, 37, has studied classical Indian music in his ancestral homeland, yet his research has delved into artificial intelligence and machine learning. Wang, 35, who earned a doctorate from Princeton, found parallels in writing music and writing computer programs. Each one has relied on the business acumen of a partner - Chordia on his wife, Prerna Gupta, 31, who is now Smule's chief product officer, and Wang on Smith, 46.

Smith was a Silicon Valley CEO who dropped out to pursue a music doctorate at Stanford, only to discover the genius of his teacher, Wang, and the potential of computer music.

Smule was originally named Sonic Mule, in homage to writer Isaac Asimov's character, "The Mule," who could influence billions to change their behavior. Smule's aims are no less ambitious. The company even has one employee, Turner Kirk, who it calls "The Mule," and who acts as a Pied Piper of smartphone musical apps.

1 billion pieces

"People have created 1 billion pieces of content using our apps," Chordia said. "How can we take technology and help people become better musicians? That's what animates me."

Technology has helped make music since the first people pounded on animal skin drums, or built stone flutes, Chordia said. "We're really thinking about ways to use new technologies to create music in fresh ways," he said.

Wang concurs. "I'm a fan of using whatever tool we have at our disposal," he said. "The reason Smule exists is mobile phones - personal, intimate, social technology that everyone has." You can add powerful to that list. Gupta points out that today's smartphone is as powerful as a 1970s supercomputer.

To critics who fear the sterility of such high technology, Chordia says the march from synthesizers to drum machines to samplers hasn't hurt music. "It's not like the synthesizer came out and no one ever played the piano again," he said. "It's a branching tree."

Need proof? Look no further than the Baldwin piano in Smule's San Francisco office.

"Making music shouldn't be about going to a conservatory, or a concert hall," Wang said. "It's in everyday life around us. It's as easy as picking up your phone."